For video playback of digital information on a digital video disk (“DVD”), the DVD player uses an audio decoder, video decoder and sub-picture decoder for playing back and respectively decoding audio, video and sub-picture information stored in a DVD.
FIG. 1 is a schematic view of a hardware structure of a DVD player 10. DVD player 10 includes a main controller 11, de-multiplexer 12, decoder 13, audio post processor 14, audio output 15, video post processor 16, video output 17, user interface 18 and controller 19. Based on user-input information, controller 19 transmits playback control signals to main controller 11. After main controller 11 reads the video information based on the playback control signals from controller 19, main controller 11 transmits audio, video, and sub-picture information, through de-multiplexer 12, respectively to audio decoder 131, video decoder 132, and sub-picture decoder 133. Main controller 11 can also receive subtitle information for screen display, e.g., for different language subtitles. A DVD can also selectively provide video information such as text data through a “Line-21” coupled between video decoder 132 and video post processor 16. “Line-21” is a type of data lines that is suitable for transmitting standardized format data according to Electronic Industries Association or EIA-608.
Sub-picture decoder 133 outputs corresponding subtitle images, generally in a bitmap format, based on decoded subtitle image display data (including, e.g., time, position, and color balance). After video post processor 17 receives subtitle images from sub-picture decoder 133, it combines the subtitle images with images output from video decoder 132. Audio decoder 131, video decoder 132, and sub-picture decoder 133 determine output timing according to a system clock, such as a video and audio data clock.
A conventional DVD player receives control signals for, e.g., fast and slow playback, reverse fast and slow playback, and playback at specific locations. These playback functions are dependent on playback information, image display time or audio output time of main controller 11. Playback timing cannot be controlled based on subtitle images.
There is thus a need in the art for a DVD system and method with flexible timing control for DVD playback and, more particularly, for a DVD system and method with improved timing control for playback based on subtitle image data.